46 NOVEMBER 2024 WorldWide Drilling Resource® Booth 269 The Potential for Geologic Hydrogen Adapted from Information by the U.S. Geological Survey (USGS) Did you know hydrogen, a gas you learned about in school, is actually the cleanest fuel? Burning it only produces pure water and heat. Engineers have found a way to harness electricity from hydrogen fuel cells by binding hydrogen and oxygen to form water. As rocket fuel, hydrogen already has an important use today. However, it may offer solutions for other hard-to-electrify sectors like long-distance flights and industrial heating moving forward. To better understand the potential for hydrogen accumulation, scientists need an improved geologic model detailing how hydrogen forms, as well as its source and movement within rock layers. USGS research geologist, Geoffrey Ellis is relying on his background in petroleum geology to create a model using the petroleum system approach. The petroleum system is a model for understanding gas and oil occurrences in geologic basins, used by petroleum geologists to guide exploration and assess undiscovered resources. The model enables geologists to examine the necessary geological factors for a successful petroleum accumulation, including organic material in source rocks and migration pathways. To determine if a petroleum accumulation is present, the geologist must identify porous reservoir rocks, and evaluate whether there are rocks capable of sealing or trapping hydrogen. To adapt the petroleum system model for hydrogen, geologists must identify natural forms of hydrogen in rock layers and understand how they are affected by natural processes, as well as how they become trapped within the rocks. Geologists are aware of numerous natural processes that produce hydrogen, but to assess its resource potential, identifying the mechanisms capable of generating large quantities is crucial. After hydrogen forms, various natural processes utilize the gas. Microbes thrive on hydrogen, and microbiologists have discovered a vast, deep biosphere powered by it. Moreover, petroleum formation from organic-rich rocks consumes any available hydrogen, which explains why it’s often found with hydrogen gases like methane and propane. Hydrogen not consumed by chemical reactions may migrate to porous rocks and form a trapped gas reserve, however, its persistence requires the presence of a competent sealing layer. For decades, geoscientists have assumed seal rocks couldn’t effectively trap hydrogen accumulations due to the gas’s small size, but studies show the diameter of a molecule of two hydrogen atoms is similar to that of a single helium atom and can be trapped by similar rock layers. USGS scientists are incorporating all these factors into their model, which will improve our understanding of the resource potential of natural hydrogen on earth. Geologic hydrogen holds great promise, but fully tapping its potential requires further research to better understand the components of the hydrogen system and develop effective exploration strategies. EXB
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